<?php

/**
 * Zend Framework
 * LICENSE
 * This source file is subject to the new BSD license that is bundled
 * with this package in the file LICENSE.txt.
 * It is also available through the world-wide-web at this URL:
 * http://framework.zend.com/license/new-bsd
 * If you did not receive a copy of the license and are unable to
 * obtain it through the world-wide-web, please send an email
 * to license@zend.com so we can send you a copy immediately.
 * @category Zend
 * @package Zend_Auth
 * @subpackage Storage
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 * @version $Id: Interface.php 24593 2012-01-05 20:35:02Z matthew $
 */
/**
 *
 * @category Zend
 * @package Zend_Auth
 * @subpackage Storage
 * @copyright Copyright (c) 2005-2012 Zend Technologies USA Inc. (http://www.zend.com)
 * @license http://framework.zend.com/license/new-bsd New BSD License
 */
interface Zend_Auth_Storage_Interface {

    /**
     * Returns true if and only if storage is empty
     * @throws Zend_Auth_Storage_Exception If it is impossible to determine whether storage is empty
     * @return boolean
     */
    public function isEmpty ();

    /**
     * Returns the contents of storage
     * Behavior is undefined when storage is empty.
     * @throws Zend_Auth_Storage_Exception If reading contents from storage is impossible
     * @return mixed
     */
    public function read ();

    /**
     * Writes $contents to storage
     * @param mixed $contents
     * @throws Zend_Auth_Storage_Exception If writing $contents to storage is impossible
     * @return void
     */
    public function write ($contents);

    /**
     * Clears contents from storage
     * @throws Zend_Auth_Storage_Exception If clearing contents from storage is impossible
     * @return void
     */
    public function clear ();

}
